The invention disclosed in this specification is primarily directed to controlling the operation of an electric fan employed for cooling purposes in cooking apparatus employing induction heating. Although the invention is specifically directed toward the utility indicated in the preceding sentence it is considered that it can be utilized in various other different, somewhat related applications.
A cooking apparatus or so-called "cook top" utilizing induction heating for cooking purposes is normally constructed so as to utilize a metal housing supporting a glass or other cook top upon which there are located a number of induction heating coils. The housing normally contains what may be referred to as an electronic "package" for use in supplying electric power to the coils used. This package of course consists of a group of interconnected electronic components. The package is normally connected to the coils used by wires which are mounted within the housing so as to extend from the electronic package to the various individual coils employed.
In order for such apparatus to operate for a prolonged period without breakdown it is necessary to utilize a fan which circulates air throughout the interior of the housing so as to maintain the temperature of the electronic components employed sufficiently low so that any heat buildup within the housing will not damage such components. Normally such a fan is connected into the circuit used to supply power to the electronic components so as to be automatically turned on each time the cooking apparatus itself is turned on and so as to be turned off each time the cooking apparatus is turned off.
While the use of a fan in this manner is desirable in preventing heat caused damage to the electronic components employed, it is also considered disadvantageous. When a fan is used in the noted manner the apparently inevitable noise associated with fan operation will be present whenever a cooking apparatus of the type indicated is used. To many individuals this is objectionable. Further, the use of a fan in the manner noted is considered unnecessary since such use does not take into consideration whether or not there is heat buildup present within a housing as noted.
As a result of these considerations it is considered that there is a need for improvement in connection with the utilization of a fan in induction heating equipment corresponding to equipment as indicated in the preceding discussion. Although it is possible to fulfill this need through the use of thermostats and various related, known temperature sensing apparatus for controlling the flow of current in an electrical circuit, it is considered that such known expedients are undesirable for any of a variety of reasons. Included within such reasons are the factors of effectiveness, cost and reliability.